Methods and apparatus for providing hypervisor level data services for server virtualization

ABSTRACT

A hypervisor virtual server system, including a plurality of virtual servers, a plurality of virtual disks that are read from and written to by the plurality of virtual servers, a physical disk, an I/O backend coupled with the physical disk and in communication with the plurality of virtual disks, which reads from and writes to the physical disk, a tapping driver in communication with the plurality of virtual servers, which intercepts I/O requests made by any one of said plurality of virtual servers to any one of said plurality of virtual disks, and a virtual data services appliance, in communication with the tapping driver, which receives the intercepted I/O write requests from the tapping driver, and that provides data services based thereon.

CROSS REFERENCES TO RELATED APPLICATIONS

This application claims priority benefit of U.S. Provisional ApplicationNo. 61/314,589, entitled METHODS AND APPARATUS FOR PROVIDING HYPERVISORLEVEL DATA SERVICES FOR SERVER VIRTUALIZATION, filed on Mar. 17, 2010 byinventor Ziv Kedem.

FIELD OF THE INVENTION

The present invention relates to virtual server environments and dataservices.

BACKGROUND OF THE INVENTION

Virtual servers are logical entities that run as software in a servervirtualization infrastructure, referred to as a “hypervisor”. Examplesof hypervisors are VMWARE® ESX manufactured by VMware, Inc. of PaloAlto, Calif., HyperV manufactured by Microsoft Corporation of Redmond,Wash., XENSERVER® manufactured by Citrix Systems, Inc. of FortLauderdale, Fla., Redhat KVM manufactured by Redhat, Inc. of Raleigh,N.C., and Oracle VM manufactured by Oracle Corporation of RedwoodShores, Calif. A hypervisor provides storage device emulation, referredto as “virtual disks”, to virtual servers. Hypervisor implements virtualdisks using back-end technologies such as files on a dedicated filesystem, or raw mapping to physical devices.

As distinct from physical servers that run on hardware, virtual serversrun their operating systems within an emulation layer that is providedby a hypervisor. Although virtual servers are software, neverthelessthey perform the same tasks as physical servers, including runningserver applications such as database applications, customer relationmanagement applications and MICROSOFT EXCHANGE SERVER®. Mostapplications that run on physical servers are portable to run on virtualservers. As distinct from virtual desktops that run client sideapplications and service individual users, virtual servers runapplications that service a large number of clients.

As such, virtual servers depend critically on data services for theiravailability, security, mobility and compliance requirements, the dataservices including inter alia continuous data protection, disasterrecovery, remote replication, data security, mobility, and dataretention and archiving policies.

SUMMARY OF THE DESCRIPTION

Aspects of the present invention relate to a dedicated virtual dataservice appliance (VDSA) within a hypervisor that can provide a varietyof data services. Data services provided by a VDSA include inter aliareplication, monitoring and quality of service.

In an embodiment of the present invention, a tapping filter driver isinstalled within the hypervisor kernel. The tapping driver hasvisibility to I/O requests made by virtual servers running on thehypervisor.

A VDSA runs on each physical hypervisor. The VDSA is a dedicated virtualserver that provides data services; however, the VDSA does notnecessarily reside in the actual I/O data path. When a data serviceprocesses I/O asynchronously, the VDSA receives the data outside thedata path.

Whenever a virtual server performs I/O to a virtual disk, the tappingdriver identifies the I/O requests to the virtual disk. The tappingdriver copies the I/O requests, forwards one copy to the hypervisor'sbackend, and forwards another copy to the VDSA.

Upon receiving an I/O request, the VDSA performs a set of actions toenable various data services. A first action is data analysis, toanalyze the data content of the I/O request and to infer informationregarding the virtual server's data state. E.g., the VDSA may infer theoperating system level and the status of the virtual server. Thisinformation is subsequently used for reporting and policy purposes.

A second action, optionally performed by the VDSA, is to store each I/Owrite request in a dedicated virtual disk for journaling. Since all I/Owrite requests are journaled on this virtual disk, the virtual diskenables recovery data services for the virtual server, such as restoringthe virtual server to an historical image.

A third action, optionally performed by the VDSA, is to send I/O writerequests to different VDSAs, residing on hypervisors located atdifferent locations, thus enabling disaster recovery data services.

There is thus provided in accordance with an embodiment of the presentinvention a hypervisor virtual server system, including a plurality ofvirtual servers, a plurality of virtual disks that are read from andwritten to by the plurality of virtual servers, a physical disk, an I/Obackend coupled with the physical disk and in communication with theplurality of virtual disks, which reads from and writes to the physicaldisk, a tapping driver in communication with the plurality of virtualservers, which intercepts I/O requests made by any one of said pluralityof virtual servers to any one of said plurality of virtual disks, and avirtual data services appliance, in communication with the tappingdriver, which receives the intercepted I/O write requests from thetapping driver, and which provides data services based thereon.

There is additionally provided in accordance with an embodiment of thepresent invention a method for providing data services within ahypervisor virtual server system, including intercepting I/O requestsfrom any one of a plurality of virtual servers to one of a plurality ofvirtual disks, and sending intercepted I/O write requests to a virtualdata services appliance that provides hypervisor data services.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be more fully understood and appreciated fromthe following detailed description, taken in conjunction with thedrawings in which:

FIG. 1 is a simplified block diagram of a hypervisor architecture thatincludes a tapping driver and a virtual data services appliance, inaccordance with an embodiment of the present invention; and

FIG. 2 is a simplified data flow chart for a virtual data servicesappliance, in accordance with an embodiment of the present invention.

DETAILED DESCRIPTION

Aspects of the present invention relate to a dedicated virtual dataservices appliance (VDSA) within a hypervisor, which is used to providea variety of hypervisor data services. Data services provided by a VDSAinclude inter alia replication, monitoring and quality of service.

Reference is made to FIG. 1, which is a simplified block diagram of ahypervisor architecture that includes a tapping driver and a VDSA, inaccordance with an embodiment of the present invention. Shown in FIG. 1is a hypervisor 100 with three virtual servers 110, three virtual disks120, an I/O backend 130 and a physical storage array 140. Hypervisor 100uses a single physical server, but runs multiple virtual servers 110.Virtual disks 120 are a storage emulation layer that provide storage forvirtual servers 110. Virtual disks 120 are implemented by hypervisor 100via I/O backend 130, which connects to physical disk 140.

Hypervisor 100 also includes a tapping driver 150 installed within thehypervisor kernel. As shown in FIG. 1, tapping driver 150 resides in asoftware layer between virtual servers 110 and virtual disks 120. Assuch, tapping driver 150 is able to access I/O requests performed byvirtual servers 110 on virtual disks 120. Tapping driver 150 hasvisibility to I/O requests made by virtual servers 110.

Hypervisor 100 also includes a VDSA 160. In accordance with anembodiment of the present invention, a VDSA 160 runs on a separatevirtual server within each physical hypervisor. VDSA 160 is a dedicatedvirtual server that provides data services via one or more data servicesengines 170. However, VDSA 160 does not reside in the actual I/O datapath between I/O backend 130 and physical disk 140. Instead, VDSA 160resides in a virtual I/O data path.

Whenever a virtual server 110 performs I/O on a virtual disk 120,tapping driver 150 identifies the I/O requests that the virtual servermakes. Tapping driver 150 copies the I/O requests, forwards one copy viathe conventional path to I/O backend 130, and forwards another copy toVDSA 160. In turn, VDSA 160 enables the one or more data servicesengines 170 to provide data services based on these I/O requests.

Reference is made to FIG. 2, which is a simplified data flow chart for aVDSA, in accordance with an embodiment of the present invention. Shownin FIG. 2 are an I/O receiver 210, a hash generator 220, a TCPtransmitter 230, a data analyzer and reporter 240, a journal manager 250and a remote VDSA 260. Remote VDSA 260 resides on different physicalhardware, at a possibly different location.

As shown in FIG. 2, I/O receiver 210 receives an intercepted I/O requestfrom tapping driver 150. VDSA 160 makes up to three copies of thereceived I/O requests, in order to perform a set of actions which enablethe one or more data services engines 170 to provide various services.

A first copy is stored in persistent storage, and used to providecontinuous data protection. Specifically, VDSA 160 sends the first copyto journal manager 250, for storage in a dedicated virtual disk 270.Since all I/O requests are journaled on virtual disk 270, journalmanager 250 provides recovery data services for virtual servers 110,such as restoring virtual servers 110 to an historical image. In orderto conserve disk space, hash generator 220 derives a one-way hash fromthe I/O requests. Use of a hash ensures that only a single copy of anyI/O request data is stored on disk.

An optional second copy is used for disaster recovery. It is sent viaTCP transmitter 230 to remote VDSA 260. As such, access to all data isensured even when the production hardware is not available, thusenabling disaster recovery data services.

An optional third copy is sent to data analyzer and reporter 240, whichgenerates a report with information about the content of the data. Dataanalyzer and reporter 240 analyzes data content of the I/O requests andinfers information regarding the data state of virtual servers 110.E.g., data analyzer and reporter 240 may infer the operating systemlevel and the status of a virtual server 110.

In the foregoing specification, the invention has been described withreference to specific exemplary embodiments thereof. It will, however,be evident that various modifications and changes may be made to thespecific exemplary embodiments without departing from the broader spiritand scope of the invention as set forth in the appended claims.Accordingly, the specification and drawings are to be regarded in anillustrative rather than a restrictive sense.

1. A hypervisor virtual server system, comprising: a plurality ofvirtual servers; a plurality of virtual disks that are read from andwritten to by said plurality of virtual servers; a physical disk; an I/Obackend coupled with said physical disk and in communication with saidplurality of virtual disks, which reads from and writes to said physicaldisk; a tapping driver in communication with said plurality of virtualservers, which intercepts I/O requests made by any one of said pluralityof virtual servers to any one of said plurality of virtual disks; and avirtual data services appliance, in communication with said tappingdriver, which receives the intercepted I/O requests from said tappingdriver, and which provides data services based thereon.
 2. Thehypervisor virtual server system of claim 1, further comprising ajournal manager in communication with said virtual data servicesappliance, which stores intercepted I/O write requests as journalentries in a virtual disk.
 3. The hypervisor virtual server system ofclaim 2, further comprising a hash generator in communication with saidvirtual data services appliance and with said journal manager, forgenerating hash values of the intercepted I/O write requests, andwherein said journal manager stores the generated hash values.
 4. Thehypervisor virtual server system of claim 1, further comprising a TCPtransmitter in communication with said virtual data services appliance,which transmits the intercepted I/O requests to a remote virtual dataservices appliance.
 5. The hypervisor virtual system of claim 1, furthercomprising a data analyzer in communication with said virtual dataservices appliance, which analyzes an intercepted I/O request and inferstherefrom the data state of the virtual server that made the I/Orequest.
 6. A method for providing data services within a hypervisorvirtual server system, comprising: intercepting I/O requests from anyone of a plurality of virtual servers to one of a plurality of virtualdisks; and sending intercepted I/O write requests to a virtual dataservices appliance that provides hypervisor data services.
 7. The methodof claim 6 further comprising journaling the intercepted I/O requests.8. The method of claim 7 further comprising generating a hash value forthe intercepted I/O requests, and wherein said journaling comprisesjournaling the generated hash values.
 9. The method of claim 6 furthercomprising analyzing an intercepted I/O request inferring therefrom thedata state of the virtual server that made the I/O request.
 10. Themethod of claim 6 further comprising sending the intercepted I/Orequests to a remote computer, thereby providing replication for saidplurality of virtual servers.